21 research outputs found
Palynological analysis of the holocene section of a new core from Tswaing Crater, South Africa
Palynological data from a new core from Tswaing Crater Lake within the savanna
biome of South Africa contributes to a better understanding of vegetation and
climate dynamics during the Holocene. A 650cm sediment core section TSW1,
with 65 samples and fourteen AMS 14C dates, covers a time period between ca
10000-2000 cal yrs BP. No pollen data are available from the lower part of the
profile (600-800cm) due to palynomorph destruction, but a single sample with a
low number of pollen grains gives a glimpse into a presumably very dry time
period at ca11300 cal yrs BP. A warm and dry early Holocene (ca 9000-7500 cal
yrs BP) is evidenced by high pollen percentages of Asteraceae, Tarchonanthus
and Dichrostachys. The mid Holocene phase from ca 7500-4000 cal yrs BP is
characterised by an increase of Burkea, Combretaceae and Podocarpus as well as
aquatics and swamp plant pollen. This suggests warm sub-humid conditions and
local moisture during this time interval. A short-term dry period occurred ca 4000
-3600 cal yrs BP characterized by a significant decline of most tree pollen
including Podocarpus, whereas Poaceae pollen increased slightly. From ca 3600 -
2000 cal yrs BP tree pollen percentages gradually increased and the presence of
Spirostachys pollen suggests a return to warm sub-humid conditions. The upper
part of the profile above a depth of 150cm shows disturbances due to salt mining
and was therefore not sampled. The palaeoclimatic interpretation of the pollen
fluctuations was supported by PCA (Principal Components Analysis). From
around ca 1800 cal yrs BP additional samples were studied in this project in
comparison to the previous study of Scott to improve the resolution. The climatic
investigation from the Tswaing pollen record of the current study supports the climatic interpretations which were inferred from the biomarker analysis by
Kristen et al., 2009. A regional comparison between the current Tswaing pollen
profile and pollen records from Wonderkrater and Lake Eteza was done in the
frame of the current study. The general palaeoclimatic changes recorded from
Tswaing pollen sequence are consistent with the pollen evidence inferred from
Wonderkrater which can attributed to regional changes in eastern South Africa.
These trends differ from those in lake Eteza, especially during the early Holocene,
which might be explained as a consequence of the generally more humid climate
in the coastal plain of KwaZulu-Natal
3-[(2-Chloro-6-methylquinolin-3-yl)methyl]quinazolin-4(3H)-one
In the title molecule, C19H14ClN3O, the quinoline and quinazoline ring systems form a dihedral angle of 80.75 (4)°. In the crystal, the molecules are linked by pairs of C—H⋯N hydrogen bonds into centrosymmetric dimers, generating R
2
2(6) ring motifs. The structure is further stabilized by C—H⋯π interactions and π–π stacking interactions [centroid–centroid distances = 3.7869 (8) and 3.8490 (8) Å]
ChemInform Abstract: Synthesis of Some New Heterocyclic Systems Bearing 2-Phenyl-6-iodo-4(3H)-quinazolinon-3-yl Moiety as Antibacterial Agents.
ChemInform Abstract: Synthesis and Chemistry of Some Novel 3-Heteroaryl-quinazolin-4-one Derivatives and Their Antimicrobial Effects.
ChemInform Abstract: Synthesis of Some New Piperazine-N,N′-bis-substituted Derivatives as Potential Biologically Active Agents.
Electronic Spectra & Acidity Constants of Schiff Bases Derived from 2-Amino-5-phynel-1,3,4-thiadiazole & Various Aromatic Aldehydes
144-14
New Quinazoline Related Derivatives with Antimicrobial Activity: Part II
Caption from Report from Red China and Xi xing man ying: [This man is] characteristic of the Border Region citizenry. In spite of primitive weapons, their fighting spirit and the fact that they are always ready to take up such arms as they possess made life miserable for [Japanese] garrisons and effective military occupation of their fields and villages impossible.China: China at War. 3. Fighting forces of Red China.A militiaman poses with a home-made land mine. Militiamen utilize any material to fashion weapons for the defense of their villages. If metal is obtainable from scrap, temple bells, etc., metal will be used for mines. Otherwise any receptacle will be fashioned into a mine including cooking pots and even hollowed out small boulders.Forman, H. (1946). Report from Red China. London: Robert Hale Limited.; Forman, H. (1946). Xi xing man ying. Shanghai: Shanghai shu bao gong si.GrayscaleForman Nitrate Negatives, Box 1
Synthesis of some new quinazoline analogs and their antimicrobial activity
Department of Pharmaceutical Chemistry, College of Pharmacy,
King Saud University, P.O. Box 2457, Riyadh 11451,
Saudi ArabiaTwo new series of 6-iodo-2,4-dithio-4(3H)quinazoline (2-9) and 6-iodo-2-thio-4-oxo-quinazoline (10-21) were prepared and screened for their antimicrobial activity. Compounds 10, 19 and 20, showed
marked broad spectrum antimicrobial activity against a panel of Gram-positive and Gram-negative bacteria and pathogenic fungi. It seems that the connected heterocyclic rings such as benzimidazole
and pyridazine, has improved the antimicrobial activities. The detailed synthesis and the antimicrobial screening of the new compounds are reported